Is partial root-zone drying an effective irrigation technique to improve water use efficiency and fruit quality in field-grown wine grapes under semiarid conditions?

We investigated the effects of partial root-zone drying (PRD) applied at different periods on leaf water relations, vegetative development, fruit yield, must and wine quality in wine grapes (Vitis vinifera L. cv. Monastrell) during a 3-year field experiment in order to determine the importance of the timing of PRD application on physiological and agronomical vine response under semiarid conditions. Two irrigation treatments were applied: conventional drip irrigation (CI) and PRD. Both treatments received the same annual water quantity. Each year the PRD treatment was applied at different periods of the growth cycle. In 1999 PRD was applied from veraison to harvest (end July–early September); in 2000 from fruit set to harvest (mid June–early September); and in 2001 PRD from budburst to harvest (mid April–early September). Leaf water relations and gas exchange during the experimental period were not significantly affected by PRD treatment. In 1999 and 2000 there was no significant treatment effect on vegetative development, yield or fruit quality. However, in 2001 (when PRD was applied from budburst to harvest), reproductive and vegetative development was clearly altered in PRD vines. Fruit set percentage and vegetative development (shoot length, pruning weight and primary and lateral leaf area) were significantly increased in PRD vines compared to CI. This resulted in both higher yield (kg per vine) (43%) and water use efficiency (40%) compared to CI vines. Berry number per cluster and cluster weight were also significantly increased in PRD vines. Notwithstanding higher yield in PRD vines and a similar berry size, the must and wine quality was not significantly altered, indicating a higher synthesis and accumulation of photoassimilates and metabolites in the berries of PRD vines. We conclude that there was an positive effect on vegetative and reproductive growth when long-term PRD was applied from the beginning of growing season (budburst), suggesting that early onset of PRD is desirable to intensify PRD response under these semiarid conditions. Nevertheless from these results we need to further investigate the long- and short-term effects of PRD, with moderate water amounts, on vegetative and reproductive development such as flowering and fruit set processes in wine grapes.     

中国野生毛葡萄芪合酶基因VqSTS11和VqSTS23调控抗白粉病的研究

利用同源克隆法得到抗白粉病的中国野生毛葡萄‘丹凤–2’芪合酶基因VqSTS11和VqSTS23的开放阅读框,并构建过表达载体;通过器官发生途径诱导不抗白粉病的欧洲葡萄‘无核白’分生愈伤组织并采用农杆菌介导法对其进行转化;经过PCR检测和Western blot鉴定,获得了5株VqSTS11超量表达植株和3株VqSTS23超量表达植株;人工接种白粉菌发现,转基因植株中白粉菌菌丝生长速度慢,孢子萌发受到一定的抑制,并且转基因植株中芪合酶基因相对表达量升高,抗病相关基因表达上调,芪类物质含量积累增多。本研究结果进一步证明中国野生毛葡萄‘丹凤–2’芪合酶基因VqSTS11和VqSTS23对白粉菌具有抗性,‘丹凤–2’可以为改良欧洲葡萄品种抗病性提供抗病基因,作为抗病育种的资源。     

酿酒山葡萄新品种‘紫晶甘露’

‘紫晶甘露’是以优质酿酒山葡萄酒品种‘左山二’为母本,‘哈桑’为父本杂交选育而成的能够单品种酿造干红酒的山葡萄新品种。果穗圆锥形,有岐肩或副穗。果实圆球形,果皮黑色,果肉绿色,无肉囊,种子2 ~ 4粒。生长势强,抗寒、抗病性极强,4年丰产,4 ~ 6年平均产量1 876 kg • km-2。果实可溶性固形物含量达到21.0%,总酸11.6 g • L-1,出汁率65.5%。     

Role of basidiomycete fungi in the grapevine trunk disease esca

Phaeomoniella chlamydospora and wood-rotting basidiomycete fungi, namely Fomitiporia spp., are known esca pathogens. However, the effect of their mixed infections and the sequence of infection on disease development is unclear. To determine the effects of single and co-inoculations on symptoms, potted Vitis vinifera ‘Crimson Seedless’ was inoculated with P. chlamydospora either alone or in combination with one of four basidiomycetes: Coprinellus radians, Fomitiporia langloisii, F. polymorpha and the novel species Tropicoporus texanus. Basidiomycetes were isolated from vines with foliar symptoms of esca in California and Texas. In sequential co-inoculations, the effects of different sequences of infection (P. chlamydospora first, basidiomycete 6 months later; and vice versa) were tested, compared to simultaneous co-inoculations. Plants inoculated with P. chlamydospora either alone or in combination with a basidiomycete (in any sequence) did not differ significantly in the length of black-streaking lesions. In plants inoculated only with a basidiomycete, the appearance of large brown lesions, coupled with the absence of this wood symptom from control plants, suggests that C. radians, F. langloisii and T. texanus are pathogenic. Foliar symptoms resembling those of esca in the field (marginal and/or interveinal scorching, combined with red and/or yellow discoloration) were statistically more frequent among plants inoculated with F. polymorpha or T. texanus, either simultaneously or following P. chlamydospora, compared to single inoculations. Sequential co-inoculations of a basidiomycete before or after P. chlamydospora were associated with similar lesion lengths, suggesting that basidiomycetes may not require infection by P. chlamydospora in order to extensively colonize the wood.     

Temporal disease dynamics and relative importance of sexual and asexual reproduction of grape downy mildew (Plasmopara viticola) in an isolated vineyard in the North Georgia Mountains,USA

The North Georgia Mountains are the southernmost region along the United States East Coast where European wine grapes (Vitis vinifera) are grown commercially. Epidemics of downy mildew, caused by Plasmopara viticola, are frequent and severe, but little is known about the epidemiology and population biology of the pathogen in this region. Disease monitoring in an experimental vineyard from 2015 to 2017 indicated that times of disease onset and progress rates were highly variable across years and cultivars. Oospores were observed microscopically, and simulation with a process-based model indicated presence of conditions favourable for oospore germination in the spring and early summer each year. A total of 409 P. viticola isolates collected over three  years were genotyped with seven microsatellite markers, revealing very high genotypic diversity, which when combined with the observation of oospores is indicative of a sexually reproducing population. Among the 409 isolates, 225 multilocus genotypes (MLGs) were identified, of which 164 were detected only once and 61 were repeated (clonal). Eight MLGs (represented by 28 isolates) were detected across years, suggesting the possibility of asexual overwintering of P. viticola in this region. Across sampling dates, the percentage of isolates belonging to nonrepeated (unique) MLGs ranged from 27.3% to 63.2%. Even towards the end of the annual epidemic, the percentage of isolates in nonrepeated MLGs was still relatively high, around 30%. These MLGs may have originated from oospores germinating late during the growing season, although incomplete sampling at earlier dates and contribution by immigration cannot be fully excluded.     

外源硅调控葡萄生理特性对低温胁迫的响应

本研究以大田葡萄品种‘梅鹿辄’为试材,采用大田喷施硅酸钾与室内低温处理相结合的方法,测定不同温度下葡萄叶片生理指标的变化,研究外源硅酸钾调控葡萄生理特性对低温胁迫的响应,探讨其提高葡萄抗寒性可能的作用机制。结果表明:低温胁迫下葡萄Inv活性被抑制,而其它指标则升高;喷施硅酸钾可显著降低低温胁迫下葡萄叶片的MDA含量,且当硅酸钾浓度为0.75%时对低温的损伤缓解作用最大;而脯氨酸、可溶性蛋白和可溶性糖含量、Inv、SPS活性及SS净活性均随硅酸钾浓度的升高而显著提高,但是可溶性蛋白含量在硅酸钾浓度为0.50%时最大,其它指标均在浓度为0.75%时最大;通过葡萄叶片各抗寒指标的隶属度值与综合评价指标看出,始花期0.75%的硅酸钾处理后葡萄抗寒性最强。综合分析,喷施硅酸钾可提高低温胁迫下葡萄叶片渗透调节物质含量,加快蔗糖转运及代谢速率,缓解活性氧累积,增强其耐寒性。     

山葡萄"双红"组培快繁技术的研究

对山葡萄“双红”组培快繁技术的研究结果表明:B5培养基为最佳基本培养基,BA0.03 mg.L-1 IBA0.2 mg.L-1为最佳激素水平配比,生根率达100%;年增殖次数8.5次,每次增殖倍数3.2倍,年增殖倍数为27.2倍;移栽炼苗平均成活率为92.5%,圃地定植成活率可达99.9%。     

Cryptic species and population genetic structure of Plasmopara viticola in São Paulo State,Brazil

Downy mildew (Plasmopara viticola) is one of the most important diseases in grape-growing areas worldwide, including Brazil. To examine pathogen population biology and structure, P. viticola was sampled during the 2015/16 growing season from 516 lesions on nine grape cultivars in 11 locations in subtropical areas of São Paulo State, Brazil. For identification of cryptic species, a subsample of 130 isolates was subjected to cleaved amplified polymorphic sequence (CAPS) analysis, and for 91 of these isolates the ITS1 region was sequenced. These analyses suggest that the population of P. viticola in São Paulo State consists of a single cryptic species, P. viticola clade aestivalis. Seven microsatellite markers were used to determine the genetic structure of all 516 P. viticola isolates, identifying 23 alleles and 55 multilocus genotypes (MLGs). Among these MLGs, 34.5% were clonal and represented 93% of the isolates sampled. Four dominant genotypes were present in at least five different locations, corresponding to 65.7% of the isolates sampled. Genotypic diversity (Ĝ = 0.21–0.89) and clonal fraction (0.58–0.96) varied among locations (populations). Most populations showed significant deviation from Hardy–Weinberg expectations; in addition, excess of heterozygosity was verified for many loci. However, principal coordinate analysis revealed no clusters among locations and no significant isolation by distance was found, suggesting high levels of migration. The results indicate that downy mildew epidemics result from multiple clonal infections caused by a few genotypes of P. viticola, and reproduction of P. viticola in São Paulo State is predominantly asexual.