1994). Desiccation tolerance in two species with recalcitrant seeds: Clausena lansium (Lour.) and Litchi chinensis (Sonn.). AbstractSeeds were collected at weekly intervals from mid-maturation to the fully ripened stage As seed development progressed, desiccation tolerance increased Desiccation tolerance of C lansium seeds was greatest at 67 days after anthesis (DAA), when they tolerated air drying for 9 days; 74 DAA was considered as physiological maturity, and their full viability was only maintained for up to 3 days of drying; overnpened seeds (88 DAA) had the lowest desiccation tolerance In L. chinensis, the desiccation sensitivity of seeds at 98 DAA (fully mature) was higher than that at 84 and 91 DAA (less mature); among the excised embryonic axes at different developmental stages, the less mature ones were less sensitive to desiccation than the fully mature ones; excised embryonic axes of the same stage were more tolerant of desiccation than whole seeds

Two inhibitors, aviglycine and propargylglycine, were tested for their ability to suppress methionine synthesis thus inhibit conidial germination and mycelial growth of Czapek-Dox liquid medium grown Fusarium oxysporum f. sp. luffaemuM. The linear inhibition range for mycelial growth was about 7.6-762.9 microM. Although aviglycine did not completely inhibit both conidial germination and mycelial growth, it showed significant inhibitory effect at 1.5 microM. The inhibition range for propargylglycine against conidial germination and mycelial growth were from 0.08 to 8841 microM and from 0.8 to 884.1 microM, respectively. Propargylglycine inhibited conidial germination and mycelial growth at a concentration of 8841 muM. The EC(50) values of aviglycine were 1 microM for conidial growth and 122 microM for mycelial growth, and the EC(50) values of propargylglycine were 47.7 microM for conidial growth and 55.6 muM for mycelial growth. Supplement of methionine released inhibition of aviglycine or propargylglycine to conidial germination. In addition, a mixture of aviglycine (1.5 microM) and propargylglycine (8841 microM) showed additive inhibitive effect than applied alone on 10 isolates. From these results, both aviglycine and propargylglycine exhibited inhibitory activity, and suggest that they can provide potential tools to design novel fungicide against fungal pathogens.

Cold and drought stresses severely limit crop production and can occur simultaneously. Although some transcription factors and hormones have been characterized in plants subjected each stress, the role of metabolites, especially volatiles, in response to cold and drought stress exposure is rarely studied due to lack of suitable models. Here, we established a model for studying the role of volatiles in tea (Camellia sinensis) plants experiencing cold and drought stresses simultaneously. Using this model, we showed that volatiles induced by cold stress promote drought tolerance in tea plants by mediating reactive oxygen species and stomatal conductance. Needle trap micro-extraction combined with GC-MS identified the volatiles involved in the crosstalk and showed that cold-induced (Z)-3-hexenol improved the drought tolerance of tea plants. In addition, silencing CsADH2 (Camellia sinensis alcohol dehydrogenase 2) led to reduced (Z)-3-hexenol production and significantly reduced drought tolerance in response to simultaneous cold and drought stress. Transcriptome and metabolite analyses, together with plant hormones comparison and abscisic acid (ABA) biosynthesis pathway inhibition experiments, further confirmed the roles of ABA in (Z)-3-hexenol-induced drought tolerance of tea plants. (Z)-3-hexenol application and gene silencing results supported the hypothesis that (Z)-3-hexenol plays a role in the integration of cold and drought tolerance by stimulating the dual function glucosyltransferase UGT85A53, thereby altering ABA homeostasis in tea plants. Overall, we present a model for studying the roles of metabolites in plants under multiple stresses and reveal the roles of volatiles in integrating cold and drought stresses in plants.

A plastochron index was established for four commercial cultivars of Phalaenopsis: Phalaenopsis 'Taisuco Carol' x (Doritaenopsis 'New Cinderella' x P. 'Isaribi') (Taiwan Sugar Corp., code No. S88-41); Phalaenopsis 'Taisuco Swan' x (P. 'Casablanca Dream' x (P. 'Hohoemi' x P. 'Grace Palm')) (code No. S88-89); Doritaenopsis 'I-Hsin Dreamer' x Phalaenopsis 'Taisuco Harmonylip' (code No. S88-104), and Phalaenopsis aphrodite. The plastochron was based on a 20-mm reference leaf length. Semilogarithmical plots of ln-transformed leaf lengths versus time and linear regression analysis were used to evaluate three criteria of the plastochron index. The results showed that leaves 3-9 of Phalaenopsis aphrodite and leaves 3-8 of the other cultivars grow exponentially (r2 values between 0.90 and 0.97). Therefore, leaves that fulfilled all three criteria for the plastochron index were leaves 3-5 of No. S88-41, leaves 3-4 of No. S88-89, leaves 5-6 of No. S88-104, and leaves 4-5 of Phalaenopsis aphrodite. However the plastochron index can not be used for the slow-growing Phalaenopsis, because two successive leaves could not be measured simultaneously during the exponential phase of leaf development. The average relative growth rate of 0.43 mm/week for Phalaenopsis aphrodite was significantly lower than that of the other three cultivars (0.52 mm/week); plastochron duration also showed significant variation among the four cultivars (P value = 0.0269). In addition, the linear relationship (r2 = 0.97-0.99) of the plastochron index plotted versus time indicates that the intervals between initiation of successive leaves was equal for each of four cultivars. Thus, for these cultivars of Phalaenopsis, leaves that emerge before the reproductive phase can not be fully assessed by the plastochron index