Abstract
Seedless fruit is a feature appreciated by consumers. The ovule abortion process is highly orchestrated and controlled by numerous environmental and endogenous signals. However, the mechanisms underlying ovule abortion in pear remain obscure. Here, we found that gibberellins (GAs) have diverse functions during ovules development between seedless pear ‘1913’ and seeded pear, and that GA4+7 activates a potential programmed cell death process in ‘1913’ ovules. After hormone analyses, strong correlations were determined among jasmonic acid (JA), ethylene and salicylic acid (SA) in seedless and seeded cultivars, and GA4+7 treatments altered the hormone accumulation levels in ovules, resulting in significant correlations between GA and both JA and ethylene. Additionally, SA contributed to ovule abortion in ‘1913’. Exogenously supplying JA, SA or the ethylene precursor 1-aminocyclopropane-1-carboxylic acid promoted ‘Bartlett’ seed death. The regulatory mechanism in which ethylene controls ovule death has been demonstrated; therefore, JA’s role in regulating ‘1913’ ovule abortion was investigated. A further study identified that the JA signaling receptor MYC2 bound the SENESCENCE-ASSOCIATED 39 promoter and triggered its expression to regulate ovule abortion. Thus, we established ovule abortion-related relationships between GA and the hormones JA, ethylene and SA, and we determined their synergistic functions in regulating ovule death.
Highlights
Pear as an important fruit, both nutritionally and commercially, and is planted worldwide
We demonstrated that GA4+7 induces ovule abortion in advance by in‐
We demonstrated that GA4+7 induces ovule abortion in advance by death, though it does not respond to GA4+7 treatment
Summary
Pear as an important fruit, both nutritionally and commercially, and is planted worldwide. Seedless fruit is desired by consumers, and various seedless species, including grapes and pears, have been bred in the past several years [1,2,3]. The fresh fruit of seedless pear has a high nutritional quality and is more convenient to consume. Identifying the genetic mechanisms and key regulatory genes involved in seedless fruit production is important for pear breeding and meeting market demand. Abnormal fertilization, female and male sterility, embryo abortion, hormone regulation and various other factors cause seedlessness [4]. We identified the seedless pear variety ‘1913’, in which seedlessness is caused by failed fertilization. A potential programmed cell death (PCD) mechanism in ovules is triggered in ‘1913’ [4]
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