Multi-trait selection of tomato introgression lines under drought-induced conditions at germination and seedling stages

ABSTRACT. To be considered drought-tolerant, a tomato cultivar is required to present some level of tolerance at all developmental stages of plant growth. Since drought tolerance is a stage-specific phenomenon, genotype assessment must be performed separately at all developmental stages. In this study, we used a multi-trait index based on factor analysis and genotype-ideotype distance (FAI-BLUP index) to properly rank 49 tomato genotypes according to their tolerance to drought stress conditions at germination and seedling stages. Seeds of 47 introgression lines, which cultivar M82 is considered drought-sensitive, and the Solanum pennellii wild accession LA 716, which is considered drought-tolerant, were subjected to a control condition, where seeds were soaked in distilled water, and a drought condition, where seeds were soaked in a polyethylene glycol (PEG) solution (-0.3 MPa). Drought stress, induced by PEG, had a significant impact on all nine germination and growth performance-related traits; there was a reduction in shoot length (SL), total length (TL), initial germination percentage (IGP), final germination percentage (FGP), germination velocity index (GVI), and germination rate (GR). In contrast, the root-to-shoot ratio (R/S) and time to reach 50% germination (T50) increased under drought stress. Root length (RL) was less affected by drought, and in some genotypes, it was even increased. As expected, LA 716 ranked closest to the drought tolerance ideotype. IL 1-4-18, IL 2-3, IL 1-2, IL 9-2, and IL 10-1 were the most drought-tolerant at the germination stage. These results will serve as guidance for breeders who are aiming at developing drought-resistant tomato cultivars.

摘要。若某番茄栽培品种被认定为耐旱品种，则需在植物生长的所有发育阶段均表现出一定程度的耐旱性。由于耐旱性具有发育阶段特异性，因此必须针对各发育阶段分别开展基因型鉴定工作。本研究采用基于因子分析与基因型-理想型距离的多性状指数（FAI-BLUP指数），对49份番茄基因型在萌发期与苗期的干旱胁迫耐受性进行合理排序。本试验所用材料包括47份渐渗系（其中栽培种M82被认为是耐旱敏感型）以及野生种潘那利番茄（Solanum pennellii）种质LA 716（被认定为耐旱型）。将上述材料的种子分别置于两种处理条件下：对照组为种子浸泡于蒸馏水，干旱胁迫组为种子浸泡于聚乙二醇（PEG）溶液（渗透压-0.3 MPa）。PEG诱导的干旱胁迫对9项与萌发及生长表现相关的性状均产生了显著影响：地上部长度（SL）、总长度（TL）、初始萌发率（IGP）、最终萌发率（FGP）、萌发速率指数（GVI）以及萌发率（GR）均出现下降。与之相反，干旱胁迫下根冠比（R/S）与达到50%萌发所需时间（T50）均有所升高。根系长度（RL）受干旱胁迫的影响较小，部分基因型的根系长度甚至出现增加。正如预期，LA 716的耐旱性得分最接近耐旱理想型。IL 1-4-18、IL 2-3、IL 1-2、IL 9-2以及IL 10-1为萌发期耐旱性最强的基因型。本研究结果可为致力于培育耐旱番茄栽培品种的育种人员提供参考依据。