Gibberellin induced shot berry formation in cv.Early Sweet is a direct consequence of high fruit set

The‘seedless’table grape industry relies mainly on stenospermocarpic cultivars,in which endosperm abortion results in berries with seed rudiments and low levels of bioactive gibberellin(GA).Application of GA to enhance berry sizing in these cultivars is often accompanied by adverse effects,one of which is increased proportions of very small berries(termed shot berries).Manual removal of these berries,which is essential to improve uniformity and market value,increases production cost and exposes the cluster to damage.Unraveling the physiological causes of shot berry formation is thus of both scientific and practical value.This study focuses on understanding the GA-mediated regulation of shot berry formation in Vitis vinifera cv.Early Sweet,known for a high proportion of shot berries,which severely damage cluster appearance.As GA is known to induce the parthenocarpic fruit set,we first tested the assumption that the parthenocarpic nature of a fruitlet is a primary cause for shot berry development.We then examined the consequence of the flower load on the proportion of shot berries in the cluster.Our data suggests that:(1)contrary to prior assumptions,the parthenocarpic nature of a fruitlet is not the primary cause for shot berry development,demonstrated by the fact that parthenocarpic fruitlets develop into a full-size berries;(2)the proportion of shot berries on a cluster is a function of the initial flower load on the inflorescence,with high initial flower load resulting in greater shot berry percentage in the cluster;(3)GA treatment bypasses the natural regulation of flower load,resulting in high fruitlet density and increased competition among fruitlets;(4)variation of flower load within the cluster influences berry size uniformity to a greater extent than does the variation in number of cluster per vine.The identity of the factors that determine the fate of a given flower on a high-load cluster remains an open question.

Characterization of NPR1 Genes from Norton and Cabernet Sauvignon Grapevine

Non-expressor of pathogenesis-related genes 1 （NPR1） plays a significant role in the defense responses of plants to pathogens by regulating the expression of defense-related genes. In the present study, we isolated two NPR1 genes from Vitis aestivalis cv. Norton and Vitis vinifera cv. Cabernet Sauvignon, which were referred to as VaNPR1.1 and VvNPR1. 1-CS, respectively. They encode a protein of 584 amino acids with a predicted molecular weight of 64.8 kDa and a theoretical isoelectric point （pI） of 5.74. The predicted amino acid sequences of VaNPR1.1 and VvNPR1.1-CS differ by only one amino acid. Over-expression of VaNPR1.1 gene in Arabidopsis npr1-1 mutant plants restores the transcriptional expression of AtPR-1 gene, though not to the full scale. This result demonstrated that a grapevine VaNPR1.1 possesses a similar function to the Arabidopsis NPR1 in the regulation of defense-related genes. Over-expression of VaNPR1.1 in transgenic Arabidopsis plant increased tolerance to salinity, but had no effect on the drought tolerance. We conclude that VaNPR1.1 is a functional ortholog of AtNPR1 and also involved in grapevine＇s response to the salt stress.

The Establishment of an Agrobacterium-Mediated Transformation Platform for the Non-Embryogenic Calli of Vitis vinifera L.

Non-embryogenic calli （NEC） was inevitably and heavily produced when grape embryogenic calli （EC） was induced from explants or during the subculture of EC.A stable and highly efficient NEC transformation platform is required to further sort out and verify key genes which determine/switch the identity of NEC and EC.In this research,a vector pA5 containing a chitinase signal sequence fused to gfp （green fluorescent protein） and an HDEL motive was used to target and immobilize into Agrobacterium strain EHA105 to establish a transformation platform for Vitis vinifera L.cv.Chardonnay NEC.It was determined that NEC 10 d after subculture was the best target tissue;30 min for inoculation followed by 3 d co-cultivation with the addition of 200 μmol L-1 acetosyringone （AS） was optimized as protocol.The use of bacterial densities as 1.0 at OD600 did not result in serious tissue hypersensitive reaction and it had higher efficiency.Kanamycin at 200 mg L-1 was picked for positive expression selection.The stable transformation of NEC was proved by reverse transcription-polymerase chain reaction techniques （RT-PCR） and fluorescent microscopy after three sub-cultures of the selected cell line.Highly efficient genetic transformation protocol of grape NEC was achieved and some of the optimized parameters were different from that reported for EC.This transformation platform could facilitate the verification of candidate somatic embryogenesis （SE） decisive genes,and the successfully transformed NEC with certain genes can also be used as bioreactors for the production of functional products,as NEC not only proliferates fast,but also keeps in a rather stable condition.

Induced defense response in red mango fruit against Colletotrichum gloeosporioides

Mango fruit exposed to sunlight develops red skin and are more resistant to biotic and abiotic stresses.Here we show that harvested red mango fruit that was exposed to sunlight at the orchard is more resistant than green fruit to Colletotrichum gloeosporioides.LCMS analysis showed high amounts of antifungal compounds,as glycosylated flavonols,glycosylated anthocyanins,and mangiferin in red vs.green mango skin,correlated with higher antioxidant and lower ROS.However,also the green side of red mango fruit that has low levels of flavonoids was resistant,indicated induced resistance.Transcriptomes of red and green fruit inoculated on their red and green sides with C.gloeosporioides were analyzed.Overall,in red fruit skin,2,187 genes were upregulated in response to C.gloeosporioides.On the green side of red mango,upregulation of 22 transcription factors and 33 signaling-related transcripts indicated induced resistance.The RNA-Seq analysis suggests that resistance of the whole red fruit involved upregulation of ethylene,brassinosteroid,and phenylpropanoid pathways.To conclude,red fruit resistance to fungal pathogen was related to both flavonoid toxicity and primed resistance of fruit that was exposed to light at the orchard.