Sterility in the rice hybrids and its significance

Richharia, R. H.; Misro, B.; Rao, R.K.

doi:10.1007/bf00033785

Cited by 11 publications

(4 citation statements)

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“…Indeed, there is evidence that crossing IR70369A with the restorer IR73885-1-4-3-2-1R produced a relatively resistant variety, despite a general susceptibility of IR70369A-derived hybrids when other restorers were used ( Table S1 ). The availability of alternative A lines for three-line hybrid breeding has increased in recent decades [ 41 , 42 , 43 ], and, furthermore, two-line breeding systems based on inducing sterility through heat (i.e., thermosensitive genetic male sterile lines, TGMS) or photosensitivity (i.e., photosensitive genetic male sterile lines, PGMS) are now available [ 44 , 45 , 46 ], which can help avoid any susceptibilities that may be linked to specific female parents.…”

Section: Discussionmentioning

confidence: 99%

Heterosis for Resistance to Insect Herbivores in a 3-Line Hybrid Rice System

Horgan,

Bernal,

Ramal

et al. 2024

Insects

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Three-line hybrid rice is produced by crossing male sterile (A line) rice with a fertility-restorer (R line). Fertile lines (B lines) are also required to maintain A line seed for breeding programs. We used a range of hybrids and their parental lines to assess the frequency and nature of heterosis for resistance to the whitebacked planthopper (Sogatella furcifera), brown planthopper (Nilaparvata lugens) and yellow stemborer (Scirpophaga incertulas). Heterosis is defined as trait improvement above the average of the parental lines as a result of outbreeding. Based on the results from a greenhouse study that challenged hybrids and their parental lines with each herbivore species, we found that susceptibility to planthoppers was associated with one of the eight A lines tested, but resistance was improved by crossing with a relatively resistant restorer. Higher frequencies of heterosis for susceptibility in comparisons between hybrids and their B lines suggest that susceptibility was not related to the cytoplasmic genomes of the associated sterile A lines. Furthermore, because none of the parental lines possessed currently effective resistance genes, improved resistance against planthoppers was probably due to quantitative resistance. In a related field trial, hybrids had generally higher yields than their fertile parents and often produced larger grain; however, they were often more susceptible to stemborers, leaffolders (Cnaphalocrocis medinalis) and other caterpillars (Rivula atimeta). This was largely a consequence of hybrid heterosis for plant biomass and was strongly affected by crop duration. We make a series of recommendations to improve hybrid breeding to reduce the risks of herbivore damage.

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Section: Discussionmentioning

confidence: 99%

Heterosis for Resistance to Insect Herbivores in a 3-Line Hybrid Rice System

Horgan,

Bernal,

Ramal

et al. 2024

Insects

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“…The early work of Kato in 1928 based on morphological and serological characteristics (Richharia et al 1962 ) confirmed the empirical classification of rice varieties in China and identified two subspecies, Japonica (Geng) and Indica (Hsien) (Oka 1988 ). The distinction also involves F1 hybrid sterility and differentiated patterns of adaptation.…”

Section: Introductionmentioning

confidence: 94%

Traces of Introgression from cAus into Tropical Japonica Observed in African Upland Rice Varieties

Beye

Billot

Ronfort

et al. 2023

Rice

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Background Asian rice Oryza sativa, first domesticated in East Asia, has considerable success in African fields. When and where this introduction occurred is unclear. Rice varieties of Asian origin may have evolved locally during and after migration to Africa, resulting in unique adaptations, particularly in relation to upland cultivation as frequently practiced in Africa. Methods We investigated the genetic differentiation between Asian and African varieties using the 3000 Rice Genomes SNP dataset. African upland cultivars were first characterized using principal component analysis among 292 tropical Japonica accessions from Africa and Asia. The particularities of African accessions were then explored using two inference techniques, PCA-KDE for supervised classification and chromosome painting, and ELAI for individual allelic dosage monitoring. Key Results Ambiguities of local differentiation between Japonica and other groups pointed at genomic segments that potentially resulted from genetic exchange. Those specific to West African upland accessions were concentrated on chromosome 6 and featured several cAus introgression signals, including a large one between 17.9 and 21.7 Mb. We found iHS statistics in support of positive selection in this region and we provide a list of candidate genes enriched in GO terms that have regulatory functions involved in stress responses that could have facilitated adaptation to harsh upland growing conditions.

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“…The resulting hybrids produce both fertile and infertile grains that are unsuitable for seed harvesting, thereby promoting the commercialization of hybrid varieties. Hybrid varieties have generally higher (up to 15%) yields than inbred rice varieties, and seed quality is generally better, thereby avoiding seed-borne diseases and reducing seed contamination with weeds [ 3 , 7 , 8 ]. However, hybrids—particularly early-generation hybrids—have often been associated with high damage from insect herbivores and diseases [ 1 , 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

Heterosis for Interactions between Insect Herbivores and 3-Line Hybrid Rice under Low and High Soil Nitrogen Conditions

Horgan,

Bernal,

Ramal

et al. 2024

Insects

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Hybrid rice results from crossing a male-sterile line (the A line) with a pollen doner (the restorer or R line). In 3-line hybrid breeding systems, a fertile B line is also required to maintain A line populations. Heterosis is defined as a condition of traits whereby the hybrid exceeds the average of the parental lines. Heterobeltiosis is where the hybrid exceeds both parents. Hybrid rice may display heterosis/heterobeltiosis for growth, yield and resistance to herbivores, among other traits. In a greenhouse experiment, we assessed the frequency of heterosis for resistance to the brown planthopper (Nilaparvata lugans (BPH)), whitebacked planthopper (Sogatella furcifera (WBPH)) and yellow stemborer (Scirpophaga incertulas (YSB)) in eight hybrids under varying soil nitrogen conditions. We also assessed plant biomass losses due to herbivore feeding as an approximation of tolerance (the plant’s capacity to compensate for damage). Nitrogen reduced resistance to all three herbivores but was also associated with tolerance to WBPH and YSB based on improved plant survival, growth and/or yields. Plant biomass losses per unit weight of WBPH also declined under high nitrogen conditions for a number of hybrids, and there were several cases of overcompensation in rice for attacks by this herbivore. There was one case of nitrogen-related tolerance to BPH (increased grain yield) for a hybrid line with relatively high resistance, likely due to quantitative traits. Heterosis and heterobeltiosis were not essential to produce relatively high herbivore resistance or tolerance across hybrids.

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Sterility in the rice hybrids and its significance

Cited by 11 publications

References 1 publication

Heterosis for Resistance to Insect Herbivores in a 3-Line Hybrid Rice System

Heterosis for Resistance to Insect Herbivores in a 3-Line Hybrid Rice System

Traces of Introgression from cAus into Tropical Japonica Observed in African Upland Rice Varieties

Heterosis for Interactions between Insect Herbivores and 3-Line Hybrid Rice under Low and High Soil Nitrogen Conditions

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