GSL2 over-expression confers resistance to Pectobacterium atrosepticum in potato.

Over-expression of the potato Gibberellin Stimulated-Like 2 ( GSL2 ) gene in transgenic potato confers resistance to blackleg disease incited by Pectobacterium atrosepticum and confirms a role for GSL2 in plant defence. The Gibberellin Stimulated-Like 2 (GSL2) gene (also known as Snakin 2) encodes a cysteine-rich, low-molecular weight antimicrobial peptide produced in potato plants. This protein is thought to play important roles in the innate defence against invading microbes. Over-expression of the GSL2 gene in potato (cultivar Iwa) was achieved using Agrobacterium-mediated gene transfer of a plant expression vector with the potato GSL2 gene under the regulatory control elements of the potato light-inducible Lhca3 gene. The resulting plants were confirmed as being transgenic by PCR, and subsequently analysed for transcriptional expression of the Lhca3-GSL2-Lhca3 chimeric potato gene. Quantitative RT-PCR analysis demonstrated that the majority of the transgenic potato lines over-expressed the GSL2 gene at the mRNA level. Based on qRT-PCR results and evaluation of phenotypic appearance, eight lines were selected for further characterisation and evaluated in bioassays for resistance to Pectobacterium atrosepticum (formerly Erwinia carotovora subsp. atroseptica), the causal agent of blackleg in potato. Three independent pathogenicity bioassays showed that transgenic lines with significantly increased transcriptional expression of the GSL2 gene exhibit resistance to blackleg disease. This establishes a functional role for GSL2 in plant defence against pathogens in potato.

Inheritance and epistasis of loci influencing carotenoid content in petal and pollen color variants of california Poppy (Eschscholzia californica Cham.).

The model basal eudicot plant California poppy (Eschscholzia californica Cham.) typically has intense yellow to orange petals and orange pollen due to pigmentation by carotenoids. Flower color variants ranging from white to yellow and orange are common. We analyzed flower color inheritance in a diverse range of white and yellow color variants with reduced carotenoid content. The inheritance of the petal-pollen color of 24 variant flowers was investigated through complementation analysis by hybridization between different color variants and screening F(1), F(2), and BC(1) populations for segregation of petal-pollen color. All white and yellow flower color variants exhibited the pleiotropic effect with each mutation influencing both petal and pollen color, with both petal and pollen color phenotypes coinherited. A total of 5 complementation groups were identified with the color variants behaving as single recessive loci. Epistatic interactions among the loci were also identified. The white/yellow California poppy color variants described in this paper represent a unique genetic resource for analysis of carotenoid biosynthesis in this basal eudicot species.