Key message Differences in the composition and the structural organisation of the extracellular matrix correlate with the morphogenic competence of the callus tissue that originated from the isolated endosperm of kiwifruit. Abstract The chemical composition and structural organisation of the extracellular matrix, including the cell wall and the layer on its surface, may correspond with the morphogenic competence of a tissue. In the presented study, this relationship was found in the callus tissue that had been differentiated from the isolated endosperm of the kiwiberry, Actinidia arguta. The experimental system was based on callus samples of exactly the same age that had originated from an isolated endosperm but were cultured under controlled conditions promoting either an organogenic or a non-organogenic pathway. The analyses which were performed using bright field, fluorescence and scanning electron microscopy techniques showed significant differences between the two types of calli. The organogenic tissue was compact and the outer walls of the peripheral cells were covered with granular structures. The non-organogenic tissue was composed of loosely attached cells, which were connected via a net-like structure. The extracellular matrices from both the non-and organogenic tissues were abundant in pectic homogalacturonan and extensins (LM19, LM20, JIM11, JIM12 and JIM20 epitopes), but the epitopes that are characteristic for rhamnogalacturonan I (LM5 and LM6), hemicellulose (LM25) and the arabinogalactan protein (LM2) were detected only in the non-organogenic callus. Moreover, we report the epitopes, which presence is characteristic for the Actinidia endosperm (LM21 and LM25, heteromannan and xyloglucan) and for the endosperm-derived cells that undergo dedifferentiation (loss of LM21 and LM25; appearance or increase in the content of LM5, LM6, LM19, JIM11, JIM12, JIM20, JIM8 and JIM16 epitopes).

Indian mustard (Brassica juncea L.) germplasm consisting 167 accessions including one check cultivar was evaluated for qualitative and quantitative traits. The present study was conducted to investigate genetic diversity and correlation among studied genotypes of B. juncea L. based on agro-morphological at NARC, Islamabad, Pakistan. To investigate the genetic diversity based on morphological characters, data was recorded on 20 quantitative and 12 qualitative traits. The calculated data was analyzed through two complementary methods, i.e. PCA (Principal Component Analysis) and cluster analysis. Among all the studied cultivars, significant diversity was recorded for different agro-morphological characters. Among all the parameters, maximum variance was recorded for pod shattering (427.2) followed by plant height (345.6), days to 100% flowering (336.2) and main raceme length (210.0). Among all the characters, the greatest and highly significant association (0.99) was found between days to maturity 50% and days to maturity 100% followed by correlation (0.86) among days to flowering 50% and days to flowering 100%, correlation value (0.71) was calculated among leaf length and leaf width. Using cluster analysis all the genotypes were divided into five major groups. It was observed that 7 out of 20 principal components with an Eigen value of ≥1.0 calculated for 73.92% of the total diversity observed between 167 accessions of Indian mustard (B. juncea L.). The contribution of first three PCs in the total PCs was 23.25, 12.87 and 11.24, respectively. Among all the investigated accessions two genotypes 26,813 and 26,817 showed great How to cite this paper: Saleem, N., Jan, S.A., Atif, M.J., Khurshid, H., Khan, S.A., Abdullah, M., Jahanzaib, M., Ahmed, H., Ullah, S.F., Iqbal, A., Naqi, S., Ilyas, M. 70potential for seeds/silique, 1000-seed weight and seed yield/plant, respectively, so these genotypes are recommended for future breeding programs for achieving promising results.

Key message Macroscopic, ultrastructural, and molecular features—like a ball shape, the presence of starch granules, and the up-regulation of genes involved in carbohydrate metabolism and secondary metabolite biosynthesis—distinguish PT regions within a callus. Abstract The modification of the mass of pluripotent cells into de novo shoot bud regeneration is highly relevant to developmental biology and for agriculture and biotechnology. This study deals with protuberances (PT), structures that appear during the organogenic long-term culturing of callus (OC) in kiwifruit. These ball-shaped regions of callus might be considered the first morphological sign of the subsequent shoot bud development. Sections of PT show the regular arrangement of some cells, especially on the surface, in contrast to the regions of OC beyond the PT. The cells of OC possess chloroplasts; however, starch granules were observed only in PTs’ plastids. Transcriptomic data revealed unique gene expression for each kind of sample: OC, PT, and PT with visible shoot buds (PT–SH). Higher expression of the gene involved in lipid (glycerol-3-phosphate acyltransferase 5 [GPAT5]), carbohydrate (granule-bound starch synthase 1 [GBSS1]), and secondary metabolite (beta-glucosidase 45 [BGL45]) pathways were detected in PT and could be proposed as the markers of these structures. The up-regulation of the regulatory associated protein of TOR (RAPTOR1) was found in PT–SH. The highest expression of the actinidain gene in leaves from two-year-old regenerated plants suggests that the synthesis of this protein takes place in fully developed organs. The findings indicate that PT and PT–SH are specific structures within OC but have more features in common with callus tissue than with organs.

Endosperm, an ephemeral and storage tissue, serves as a source of nutrition and protection during embryo development and germination. It can be used for the cultivation of polyploid plants in vitro. Here, results of plant regeneration and acclimatization from the endosperm-derived calli of four cultivars of Actinidia arguta has been presented. Seeds excised from fresh fruit and dry seeds stored for one year served as the sources of endosperm explants of selected tetraploid cultivars of A. arguta. Callus Induction Medium (CIM; containing 0.25, 0.5, or 1 mg/l of TDZ) and Actinidia Endosperm Medium (AEM; containing 2 mg/l of 2,4-D and 5 mg/l of kinetin) were used to study the organogenic responses of the calli. On AEM, the source of explant did not significantly affect the rate of callus induction for any of the tested cultivars; no organogenic events were observed. In contrast, on CIM both the source of explants and the cultivar origin caused significant differences in callus formation and subsequent organogenic events. Histological and ultrastructural analyses revealed the adventitious nature of shoot bud formation on these media. The most efficient elongation of shoot buds was achieved after transferring organogenic calli with adventitious shoot buds to a medium supplemented with zeatin or meta-topolin. Robust root induction with minimal basal callus formation occurred on the medium with indole-3-acetic acid. Flow cytometric analysis revealed that the nuclear DNA content in the leaves of some regenerants was approximately 50 % higher (4.5 pg/2C) than that in leaves from the tetraploid seedlings (3.1 pg/2C),which confirmed that those regenerants originated from the endosperm. The regeneration of such hexaploid plants was more efficient when endosperm from fresh seeds served as an explant; therefore, fresh rather than dry seeds are recommended for endosperm-derived plant production. The hexaploid plants of A. arguta can serve as an important source of breeding material.

Endosperm, an ephemeral and storage tissue, serves as a source of nutrition and protection during embryo development and germination. It can be used for the cultivation of polyploid plants in vitro. Here, a protocol of plant regeneration and acclimatization from the endosperm-derived calli of Actinidia arguta has been developed. Seeds excised from fresh fruit and dry seeds stored for one year served as the sources of endosperm explants of selected tetraploid cultivars of A. arguta. Callus Induction Medium (CIM; containing 0.25, 0.5, or 1 mg/l of TDZ) and Actinidia Endosperm Medium (AEM; containing 2 mg/l of 2,4-D and 5 mg/l of kinetin) were used to study the organogenic responses of the calli. On AEM, the source of explant did not significantly affect the rate of callus induction for any of the tested cultivars. Similarly, no organogenic events were observed. In contrast, on CIM both the source of explants and the cultivar origin caused significant differences in callus formation and subsequent organogenic events. Histological and ultrastructural analyses revealed the adventitious nature of shoot bud formation on these media. The most efficient elongation of shoot buds was achieved after transferring organogenic calli with adventitious shoot buds to a medium supplemented with zeatin or meta-topolin. Robust root induction with minimal basal callus formation occurred on the medium with indole-3-acetic acid. Flow cytometric analysis revealed that the nuclear DNA content in the leaves of some regenerants (4.5 pg/2C) was approximately 50% higher than that in the tetraploid seedlings (3.1 pg). This finding confirmed that those regenerants originated from the endosperm. The regeneration of hexaploid plants was more efficient when endosperm from fresh seeds served as an explant; therefore, fresh rather than dry seeds are recommended for endosperm-derived plant production. The hexaploid plants of A. arguta can serve as an important source of breeding material.