Development of molecular markers for the assessment of moisture stress tolerance in eggplant (Phase 2)

E. F. Delfin

Date

2016

Abstract

Greenhouse and filed verification trials were conducted to identify drought tolerant eggplant variety/accessions. The greenhouse verification trials identified promising accessions; PHL 12232, PHL 1519 and PHL 4841 which were evaluated under field condition along with other selected eggplant accessions and reference varieties, Mara and Mistisa. Tolerant and intolerant accessions were identifies in the field trial. Drought tolerant entries were PHL 5764, PHL 4841, PHL 2778 while PHL 1602 was identified drought intolerant entry. For the field trial, drought treatment was imposed at 5 weeks after transplanting by withholding irrigation for 2 weeks. Drought treatment was terminated early due to heavy rainfall occurrence at 3 weeks after drought imposition. PHL 2789 produced the highest fruit yield for both the control and drought conditions followed by PHL 2778. The yield of these two entries were significantly higher than the reference varieties, Mistisa, DLP and Mara for both growing conditions. This observation was further observed during the recovery period with PHL 2789 producing significantly higher than the 3 checks while PHL 2778 produce higher yield than Mistisa and DLP. Each genotype showed reductions in yield in both drought and recovery period, with genotypes showing different magnitudes of reduction. In terms, of relative yield, 2 entries PHL 5764 and PHL 484 showed consistently low yield reduction (less than 20%) during drought and recovery period. Further verification of fruit yield of promising accessions showed the adverse effect of drought on fruit field with reductions ranging from 11% to 59%. The trial was also affected by bacterial wilt infection such that yield loss could have been also influenced by the disease occurrence. The promising entries previously selected in terms of yield such as accessions PHL 2789 and PHL 2778 had yield reductions of 25 and 11% respectively. On the other hand, accession PHL 1602 which also had high yield reduction in the previous trial, had yield reduction of 46%. The four selected entries were also subjected to antioxidant activity assay using 2, 2-Diphenyl-1-picryhydrazyl (DPPH). The promising drought tolerant entries showed in increasing trend in terms of percent scavenging activity until the 10th day after drought deposition (DAI) whereas PHL 1602, the drought intolerant accession was observed to have reduced activity at 10 DAI. Polymorphic markers were identified for he initial selection f PHL 4841 and PHL 2789 and Mara and Mistisa (Female parent). Six polymorphic markers (EM141, EME05B09, EM133, emh11O01, emf21I02 and EM117) were identified for the cross Mistisa x PHL 4841 and four markers (CSM20, eme09E09, EM13 1 and EE063)for the cross Mara x PHL 2789. These 10 primer pairs were used in the hybridity testing of the progenies of the two crosses. The low percentage of SSR marker polymorphism was attribute to the self-pollinating nature of eggplant. Low percent polymorphism was also observed from the selected accessions in the field. The percent polymorphism are a follows; 12.4% for the cross PHL x PH5764, 6.8% for PHL 1602 x PHL 4841 and 10.80% for PHL 1602 x PHL 2778. SSR marker screening for PHL 1602 x PHL 2789 cross is not completed yet with only 59 markers screened the low percent polymorphism observed indicate the relatively low genetic diversity among the parental crosses used. The identified SSR polymorphic markers successfully used in hybridity testing of F1 progenies derived from selected eggplant genotypes. For F1s derived from M9stisa x PHL 4841 cross, only markers EM117, emh11O01, emf21I02 and EM141 were able to distinguish hybrids out of the six markers used in this cross. Thus, the efficiency of the marker in terms of identifying hybrids ranged from 36.67%-96.67%. for the cross between Mara PHL 27 89, markers CSM20 and EM131 all 30 progenies exhibited the presence of bands fr om both parents. Moreover, the six SSR polymorphic markers used in the hybridity testing of progenies from the cross PHL 1602 x PHL 2778 showed 42.86-100% efficiency while percent hybridiy among the 35 progenies tested ranged from 71.43-100 %. The identified polymorphic SS markers were also used to assess the genetic diversity among selected eggplant accessions which exhibited different drought responses. Twenty eggplant accessions from Turkey, China, India Laos, Taiwan, Africa and difference provinces of the Philippines were analyzed for genetic diversity.

Language

English

Document Type

Article

Pages /Collation

73 leaves

En – AGROVOC descriptors

SOLANUM MELONGENA; AUBERGINES; VARIETIES; GENETIC MARKERS; MOISTURE CONTENT; DROUGHT RESISTANCE; DROUGHT STRESS; TOLERANCE; GENETIC POLYMORPHISM; DNA; EXPERIMENTATION

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