Abstract

Rough lemon is indigenous and has wide adaptability in Indian citriculture. Rough lemon and Volkamer lemon are comparable in horticultural performance and their resistance against biotic and abiotic stresses are almost similar but Volkamer lemon has better adaptability in different agroclimatic conditions. To improve Volkamer lemon hybridization has been attempted with Kinkoji (citrus greening tolerance), Swingle citrumelo (Phytophthora resistance), and Cleopatra (salinity tolerance). Polyembryony in Volkamer lemon and absence of the heritable morphological markers (Cleopatra) are limiting factors for hybrid identification and morphological characters are not being segregated in Kinkoji and Swingle citrumelo at early stage, then molecular markers are employed for detection of putative zygotic seedlings. We performed hybridization between Volkamer lemon (♀), Kinkoji (B cross) (58 F₁) (♂), Swingle citrumelo (D cross) (71 F₁) (♂), Cleopatra (N cross) (83 F₁) (♂) and discriminate the hybrids by using 25 SSR markers. The fifteen markers were found efficient for hybrid identification (> 71% hybrids detected). CCSME23 (88.21%) marker has detected 187 hybrids in all crosses thereafter, 184 hybrids detected each by HvSSRCS-2, HvSSRCS-135, HvSSRCS-237, HvSSRCM-92 and HvSSRCM-466 with 86.79%. A total of 44 qualitative and 18 quantitative characters were analysed. Fifteen qualitative and six quantitative characters were found significant variability in leaf, spine, branch, and stem. Sufficient amount of genetic variability was detected through phylogenetic analysis and population structure analysis showed two subpopulations in B and N cross but in D cross five subpopulations were detected. After primary screening, nine F₁ hybrids for citrus greening tolerance and twelve F₁ hybrids for Phytophthora tolerance were identified. The newly developed F₁ hybrids exhibited phenotypic and genetic diversity along with disease tolerance. These potential hybrids may be recommended for commercial citriculture after thorough horticultural evaluation.

中文翻译：

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形态性状与微卫星标记相结合的柑橘砧木杂交种鉴定及多样性分析

摘要

粗柠檬是本土品种，在印度柑橘栽培中具有广泛的适应性。粗柠檬和Volkamer柠檬的园艺性能相当，对生物和非生物胁迫的抵抗力几乎相似，但Volkamer柠檬在不同农业气候条件下具有更好的适应性。为了改善 Volkamer 柠檬，已尝试与 Kinkoji（柑橘绿化耐受性）、Swingle citrumelo（抗疫霉性）和 Cleopatra（耐盐性）进行杂交。 Volkamer柠檬的多胚性和缺乏可遗传的形态标记（Cleopatra）是杂种鉴定的限制因素，并且Kinkoji和Swingle柑橘的形态特征在早期没有被分离，然后利用分子标记来检测假定的合子苗。我们在 Volkamer 柠檬 (♀)、Kinkoji (B cross) (58 F ₁ ) (♂)、Swingle citrumelo (D cross) (71 F ₁ ) (♂)、Cleopatra (N cross) (83 F ₁ ) ( ♂）并使用 25 个 SSR 标记来区分杂交种。发现这 15 个标记对于杂种鉴定是有效的（检测到的杂种超过 71%）。 CCSME23 (88.21%) 标记在此后的所有杂交中检测到 187 个杂种，其中 HvSSRCS-2、HvSSRCS-135、HvSSRCS-237、HvSSRCM-92 和 HvSSRCM-466 各检测到 184 个杂种，检测率为 86.79%。总共分析了 44 个定性特征和 18 个定量特征。在叶、刺、枝和茎中发现了 15 个定性和 6 个定量性状的显着变异。通过系统发育分析和群体结构分析检测到足够量的遗传变异性，显示B和N杂交中检测到两个亚群，但在D杂交中检测到五个亚群。经过初步筛选，鉴定出9个耐柑橘黄龙病的F _{1杂种和12个耐}疫霉的F ₁杂种。新开发的 F ₁杂种表现出表型和遗传多样性以及抗病性。经过彻底的园艺评估后，这些潜在的杂交品种可能会被推荐用于商业柑橘栽培。